1. Univ. ov TehranIntroduction to Computer Network1 An Introduction Computer Networks An Introduction to Computer Networks University of Tehran Dept. of EE and Computer Engineering By: Dr. Nasser Yazdani Lecture 1: Introduction

2. Univ. ov TehranIntroduction to Computer Network2 Outline Agenda Policy, Grading, reading materials, etc. Communication. Overview and history of the Internet

3. Univ. ov TehranIntroduction to Computer Network3 Agenda To establish a base for future computer network work and study. Review networking technologies, protocols. Finally, prepare to perform some projects in computer networks which are essential in national development, designing and building switches, routers, etc.

4. Univ. ov TehranIntroduction to Computer Network4 Course Materials Course Web page http://ece.ut.ac.ir/classpages/Networks/ visit regularly Textbook “Computer Networks, A system approach”. Peterson & Davie 3 rd edition Other useful books A. Tanenbaum, Computer Networks R. Stevens, TCP/IP Illustrated (vol 1) S. Keshav, An Engineering Approach to Computer Networking Kurose and Ross, Computer Networking Walrand, Communication Networks, 2nd Ed

5. Univ. ov TehranIntroduction to Computer Network5 Grading Homework assignments, around %30 3-4 five homework A small project. Severe late penalties! Course involve programming on C/C++ in Unix environment. Few small quizs around %10 Midterm exam around %30. Final exam around %30. There is a %40 cut off on total exam points.

6. Univ. ov TehranIntroduction to Computer Network6 Prerequisition General knowledge in Computer engineering. C programming. Knowledge of UNIX (LINUX) system and programming. Fluency in English, specially reading.

7. Univ. ov TehranIntroduction to Computer Network7 How to survive this course Materials sound simple and easy, but they are not. Do not leave everything to the exam night!. Not copy the homework!, try them by yourself. You can read the course by yourself, but the class makes the life for you easier.

8. Univ. ov TehranIntroduction to Computer Network8 Some Ground Rules  Let’s make this educational and enjoyable.  It’s a big class, I enjoy questions and ideas from the class.  Ask questions and raise points.  Identify yourself when you ask questions.  Listen to other people’s questions.  Be here.  Be here on time.

9. Univ. ov TehranIntroduction to Computer Network9 Communication as a human being need. Base of community Collection of trees is not a community. Transferring data, knowledge, experience among people Base of civilization. Psycological need. Love, affection. Just talking. Releasing someone. Base of Culture.

10. Univ. ov TehranIntroduction to Computer Network10 Primary Communication means Language Conventions Body Language, Meta language. Universal. Problems: Limited in Time (delay) and space (domain). We are struggling all the history to overcome these limitation.

11. Univ. ov TehranIntroduction to Computer Network11 Communication elements Producer, Sender Speaker (in conversation) Consumer, Receiver Listener They both do have processing-limitation Message- Talk Transfer media, like air Substance Capacity (very limited) Delay (considerable)

12. Univ. ov TehranIntroduction to Computer Network12 Type of communication One to one Direct talk. One to many Talks, conferencing Many to Many Like mass media, new paper. Domain of communication Small, primary society Medium, more developed society. Large, more advance society.

13. Univ. ov TehranIntroduction to Computer Network13 First Step- Writing One of the most important human being invention. (Why?) Overcome the primary limitations. Time: By writing it down. Space: Distributing more copies, library, post, etc. Problems: Indirect Communication, Through paper. Slow in producing and consuming Need proficiency Encoding message

14. Univ. ov TehranIntroduction to Computer Network14 Next Step- Mailing Distribute messages as fast as and as far as possible. Overcome mostly space limitation, while widen the domain of communication. Media- human being network system. Indirect communication. Encoded message Slow.

15. Univ. ov TehranIntroduction to Computer Network15 New wave- Telegraph In 1837, Samuel B. Morse invented it. Text message is encoded by dot and dashed (binary, digital system). Message switching, human coding for efficiency, and hop by hop routing. Fast transmission, (Time limitation) Slow production (25-30 word/min) The daily Telegraph.

16. Univ. ov TehranIntroduction to Computer Network16 Telephone In 1876, While working on multiplexing telegraph, invented By A. Graham Bell. One to one, completely real time communication. No need to proficiency. Fast, (time limitation) Easy to use or produce data. Exponential growths, 1000 in 1877 to 50,000 in 1880

17. Univ. ov TehranIntroduction to Computer Network17 Broadcast media Printing, news papers, Easy to reproduce the same data. Easy to distribute message. Slow in producing and contribution. Radio Easy to distribute message. Fast in producing and contribution of message. Limited of type of message, only voice. TV All like radio, but with reach data.

18. Univ. ov TehranIntroduction to Computer Network18 Computer Network Fast in producing, processing, distributing and consuming messages. No limitation in time and space. Support different type of communication. Mass media, news group. One to many, mailing list. One to one, mail, chat, talk. Support of different type of message, data Only problem, need proficiency.

19. Univ. ov TehranIntroduction to Computer Network19 History of the Internet 70’s: started as a research project, 56 kbps, < 100 computers 80-83: ARPANET and MILNET split, 85-86: NSF builds NSFNET as backbone, links 6 Supercomputer centers, 1.5 Mbps, 10,000 computers 87-90: link regional networks, NSI (NASA), ESNet(DOE), DARTnet, TWBNet (DARPA), 100,000 computers 90-92: NSFNET moves to 45 Mbps, 16 mid-level networks 94: NSF backbone dismantled, multiple private backbones Today: backbones run at 10 Gbps, around160 millions computers in 160 countries

20. Univ. ov TehranIntroduction to Computer Network20 Growth of the Internet Number of Hosts on the Internet: Aug. 1981 213 Oct. 1984 1,024 Dec. 1987 28,174 Oct. 1990 313,000 Oct. 1993 2,056,000 Apr. 1995 5,706,000 Jul. 1997 19,540,000 Jul. 1999 59,249,900 Jul. 2001 117,288,000 Data available at: http://www.netsizer.com/

21. Univ. ov TehranIntroduction to Computer Network21 Recent Growth (1991-2000)

22. Univ. ov TehranIntroduction to Computer Network22 Recent Growth (by 2004)

23. Univ. ov TehranIntroduction to Computer Network23 Services Provided by the Internet Shared access to computing resources telnet (1970’s) Shared access to data/files FTP, NFS, AFS (1980’s) Communication medium over which people interact email (1980’s), on-line chat rooms, instant messaging (1990’s) audio, video (1990’s) replacing telephone network? A medium for information dissemination USENET (1980’s) WWW (1990’s) replacing newspaper, magazine? audio, video (1990’s) replacing radio, CD, TV?

24. Univ. ov TehranIntroduction to Computer Network24 Today’s Vision Everything is digital: voice, video, music, pictures, live events Everything is on-line: bank statement, medical record, books, airline schedule, weather, highway traffic, toaster, refrigerator … Everyone is connected: doctor, teacher, broker, mother, son, friends, enemies

25. Univ. ov TehranIntroduction to Computer Network25 What is Next? Electronic commerce virtual enterprise Internet entertainment interactive sitcom World as a small village community organized according to interests enhanced understanding among diverse groups

26. Univ. ov TehranIntroduction to Computer Network26 What is Next? Electronic democracy little people can voice their opinions to the whole world little people can coordinate their actions bridge the gap between information haves and have-not’s Electronic terrorism hacker can bring the whole world to its knee

27. Univ. ov TehranIntroduction to Computer Network27 Industrial Players Telephone companies own long-haul and access communication links, customers Cable companies own access links Wireless/Satellite companies alternative communication links Utility companies: power, water, railway own right of way to lay down more wires

28. Univ. ov TehranIntroduction to Computer Network28 Industrial Players Medium companies own content Internet Service Providers Equipment companies switches/routers, chips, optics, computers Software companies

29. Univ. ov TehranIntroduction to Computer Network29 Commercial Internet after 1994 NSF Network Regional ISP America On Line IBM Bartnet Campus Network Joe's Company Stanford Xerox Parc Berkeley NSF Network Internet MCI UUnet SprintNet Modem IBM

30. Univ. ov TehranIntroduction to Computer Network30 Backbone ISP Internet Physical Infrastructure Residential Access Modem DSL Cable modem Satellite Enterprise/ISP access, Backbone transmission T1/T3, DS-1 DS-3 OC-3, OC-12 ATM vs. SONET, vs. WDM Campus network Ethernet, ATM Internet Service Providers access, regional, backbone Point of Presence (POP) Network Access Point (NAP)

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37. Univ. ov TehranIntroduction to Computer Network37 Homework 0 Install Linux on your computer Try to be professional on Unix if you are not so. For Communication Engineer: Learn C/C++ programming well on Unix environment. Your first assignment will come soon!.

38. Univ. ov TehranIntroduction to Computer Network38 Next Lecture Computer network foundation. Read Chapter 1